Production of organosilanes



Patented May 26, 1953 Siegfried "Nitzsche, Burghausen,

Egon Wiberg and .Munich, Germany No Drawing. lap :nial No. 1254;436.

6 Claims.

The preparation of organosilicon halides by reaction of alkyl chlorides with silicon and by the reaction of silicon tetrachloride with Grignard reagents has heretofore been described.

The present invention relates to the preparation of organosilicon halides by new and improved methods.

In accordance with the present invention, a silicon subhalide is reacted at elevated temperature with a chlorohydrocarbon, preferably, but not necessarily, in the presence of a catalyst.

The silicon subhalides have heretofore been described (Robert Schwarz, Angewandte Chemie, vol. 51, No. 22 (1938) pages 328 to 331). Those which are employed in the present process are solids and have a halogen content less than equivalent to SiX2.

A wide variety of products may be prepared in accordance with the method hereof, depending upon the starting material. Thus, compounds such as methyl chloride, vinyl chloride, phenyl chloride, allyl chloride and the like, may be employed. By reaction of silicon subhalides with these materials, it is possible to obtain methylchlorosilanes, vinylchlorosilanes, phenylchlorosilanes and allylchlorosilanes, respectively. The present process accordingly has a much wider latitude of operability than does the process in which an alkyl or aryl chloride is reacted with elemental silicon.

The present process is conducted with the chlorohydrocarbon in fluid state, either in liquid or vapor phase. The reaction is preferably conducted in the presence of a catalyst. Suitable catalysts are the salts and oxides of heavy materials, for example, cop er, which may be employed as copper oxide, as a copper salt or a mixture of the two. Likewise, metallic copper may be introduced and converted in situ to a salt or oxide. The process may likewise be conducted if desired in the presence of gases such as hydrogen, hydrogen halide or hydrocarbons, and the like.

The process may be readily performed by filling a reactor tube with the silicon subhalide and catalyst and passing the chlorinated hydrocarbon vapor through the tube at a temperature of 300 C. or above. The product which is withdrawn from the tube in vapor phase may be fractionated to recover acted chlorohydrocarbon may reactor. In continuous operation of this variety, the chlorinated hydrocarbon may either liquid or vapor phase. When a vapor phase type of reaction is conducted, pressure is employed on the reactor tube to maintain desired phase conditions.-

oberbayern, and

Askan Hertwig, Seelze,

.In GermanyAug half is methyltrlchlorosilane 'lication November 1, 1951, Se-

was, 1am

Likewise, the present process may be conducted by a batch type of operation. Thus, the silicon subhalide may be loaded in a bomb or autoclave and the hydrocarbon halide introduced into the bomb or autoclave. When a hydrocarbon is employed which is normally a liquid, it may be loaded at atmospheric pressure. In case of volatile hydrocarbon halides it is frequency desirable to introduce these reactants into the bomb or autoclave under pressure. The bomb is then heated to reaction temperature and cooled. The liquid product may then be fractionated to recover the organochlorosilanes, or it may be employed directly for the preparation of siloxane resins by hydrolysis thereof.

The following examples illustrate the process hereof but should not be taken as limiting the scope of the present invention.

Example 1 Methyl chloride was continuously introduced at atmospheric pressure into a reactor containing silicon subchloride (SiC11.1). This silicon subchloride is a solid material. The reactor was maintained at a temperature of 320 C. The efiiuent product was condensed and found to contain methylchlorosilanes.

Example 2 The method of Example 1 was repeated, but employing ethyl chloride instead of methyl chloride. The condensed product was found to contain ethylchlorosilanes.

Example 3 Methyl chloride was introduced into a reactor for twelve hours at atmospheric pressure at a temperature of 330 0., which reactor contained 45 grams of SiChi in mixture with 9.5 grams of pyrophoric copper. The efiluent product was condensed, whereby there were obtained '70 cc. of liquid. This liquid product contained about per cent of methylchlorosilanes.

Example 4 A reaction tube cm. long was loaded with 4.5 grams of SiCl1.1 mixed with 0.95 gram of pyrophoric copper. The reaction tube was heated to 350 C. Methyl chloride was introduced into the tube in vapor phase at a rate corresponding to one to two drops liquid methyl chloride. The methyl chloride so introduced was diluted with an equal volume of hydrogen. After twelve hours 8 cc. of product had been collected. Of the methylchlorosilanes so collected, about and half dimethyldichlorosilane, although the mixture contains which the reaction is conducted in the presence small percentages of silicon tetrachloride, triof hydrogen halide.

ch rosilane and trimethylchlorosilane. e method of preparing methylchloro- That which is claimed is: silanes comprising contacting methylchloride at The method of preparing organosilicon com- 5 a tem erature above 300 C with a solid silicon pounds which comprises contacting a, chlorohysubchloride containing an average of less than 2 drocarbon at a temperature above 300 C. with a chlorine atoms per silicon atom. 1 solid silicon subchloride.

2. The method in accordance with claim 1 in SIEGFRIED NI'I'ZSCHE. Which the hydrocarbon halide is in vapor phase 10 EGON WIBERG. during reaction. ASKAN HERTWIG.

3. The method in accordance with claim 1 in which the hydrocarbon halide is in liquid phase References Cited in the file Of this patent during r a i UNITED STATES PATENTS 4. The method in accordance with claim 1 in 15 N her N D t which copper is present as a catalyst in the mixg 355 1 1 a e 51 ture with silicon chloride. Lleber e a y 10, 19

5. The method in accordance with claim 1 in 2580159 DePree et a1 1951 

1. THE METHOD OF PREPARING ORGANOSILICON COMPOUNDS WHICH COMPRISES CONTACTING A CHLOROHYDROCARBON AT A TEMPERATURE ABOVE 300* C. WITH A SOLID SILICON SUBCHLORIDE. 